-K4 



RKPORT 



METHODS FOR 







lO 



For the American Association of Official 
Agricultural Chemists. 



By R. C. KEDZIE, Reporter. 



LAXSIXG: 

D. D. Thorp, Printer and Binder. 
1891. 



6 

the soil distilled water (amnioiiia-free) sufficient to moisten all the 
soil, and let the whole stand undisturbed for half an hour, then 
add more pure distilled water, and if the filtration is too slow use 
the filter-pump till a liter of filtrate is secured. If the soil extract 
is cloudy, filter through a plain filter. Each cubic centimeter of 
filtrate contains the w^ter-soluble materials of a gram of air-dry 
soil. 

9. Soluble solids. — Evaporate 100 c. c. to dryness on the water- 
bath in a tared dish to determine the percentage of water-soluble 
materials in the soil ; each gram of residue representing a i)er 
cent of such materials. Test this dry residue for nitrates by 
pouring over it 10 c. c. of O.P. H» 8O4 holding in solution tliree or 
U>\xv milligrams of sulfate of brucia. 

10. CJilorkles. — Titrate 100 c. c. with standard decinormal argen- 
tic nitrate with two drops of solution of KsCrO^ as indicator. 
Titrate in white porcelain dish and view the reaction through a 
"yellow glass plate of such tint as will eliminate the color of the 
chromic solution. The reaction will then be sharply defined. 
More than one part of soluble chlorides in one thousand of soil is 
injurious to agricultural plants. 

11. Sulfates. — Precipitate the soluble sulfates in 100 c. c. with 
BaCU in presence of a few drops of HCl. and estimate the soluble 
sulfates. 

■Reserve the rest of the water solution (8) for the estimation of 
nitrates (30). 

AciD-8uLU]{LE Materials. 

In the following scheme for soil analysis it is recommended to 
use the air-dry soil from the sample bottle for each separate in- 
vestigation. A determination made -once for all of hj'groscopic 
moisture and of water of combination on a separate specimen of 
air-dry soil will aftord corrections for all the other samples used. 
It is not desirable to ignite the soil before analysis, or to lieat it so 
as to change its chemical properties. 

In an agricultural chemical analysis the object is to find the 
kind and quantity of soil materials availaljle for the growing })lant. 
The reserve or inactive materials are not objects of immediate 
concern. Prof, llilgard takes C. P. IICI. of specific gravity 1. 11. '> 
as the solvent for soil materials, which may be supposed to fully 
represent the solvent action that may be secured by water and 
other solvents in the soil, and the at-tion of the roots of growing 

n& 4 W6 



7 

plants or other corroding agents. The same acid and of the same 
strength is here recommended, but with a modified form of using 
the same. Instead of digesting the soil with this acid in a 
covered beaker, with liability to continual variation of strength of 
the acid, it is proposed to use the acid with constant strength 
except so far as it may be neutralized by combination with the soil 
minerals. 

Instead of a porcelain beaker covered with a watch glass I pro- 
pose for the soil digestion a four-ounce vial of Bohemian glass, 
with a flat-topped ground glass stopper. The small steam bath 
is a copper vessel eight inches in diameter and five inches deep, 
with vertical sides ; the cover has four openings through which 
the vials nuiy readily pass down two and three-quarter inches to a 
perforated false bottom upon which the vials rest, and the space 
of two and a quarter inches below the false bottom serves for the 
hot water chamber of the steam bath. T'hrough the center of 
the cover and of the false bottom a vertical tube, open at both 
ends, extends nearly to the bottom of the vessel, for pouring in 
water to replenish the waste ; or a side tube near the bottom of 
the hot water chamber may be connected with a water reservoir 
to keep the water in the steam bath at a constant level. A Bun- 
sen burner serves to heat up the steam bath and to keep the body 
of the vials at the constant heat of boiling water. When such a 
bath is set to work the digestion can go forward day and night 
with very little care and attention. If the vials charged for diges- 
tion are placed in the apparatus when cold and then heated up to 
steam heat, no trouble is found from the vials breaking. AVhen 
the vials are proj)erly charged and the escape of acid prevented, 
thirty-six to forty hours of continuous digestion will be as effect- 
ive as five days of intermittent digestion in a covered beaker. 

12. Acid digestion of the soil. — Weigh five grams of the air- 
dry soil into a four-ounce Bohemian vial, add 50 c. c. of C.P. HCl. 
sp. gr. 1.115, insert glass stopper, wire it securely, place in steam 
bath and digest for thirty-six to forty hours at the temperature of 
boiling water. Pour the contents of the vial into a small beaker, 
wash out the vial with distilled water, add the washings to the 
contents of the beaker, pour into this 2 c. c. of HNOs to peroxidize 
the iron and oxidize organic matter, and evaporate the contents 
of the beaker to complete dryness over the water bath. Cool the 
beaker, add 10c. c. of C.P. HCl. sp. gr. 1.115 and 50 c. c. of distilled 
water and heat to near boiling. Filter from sand and silica, 



8 

wash the filter with distiHetl water till tlie tiltrate sliows no reac- 
tion with sihx-r nitrate, and make the liltrate u]) to500e, c. (Solu- 
tion A). 1011 f. c. of which represents the soluhle materials from one 
gram of air-drv soil. 

13. Siiiid (did silica. — Dry the filter and insoluble residue from 
A, transfer the residue to a tared platinum dish, burn the filter 
and add its ash to the dish, heat the dish and contents, at first 
gentl}' to avoid spurting of silica, then intensely to destroy organic 
matter, cool in desiccator and weigh. The increase of weight — 
minus the filter ash — represents the sand and silica. Boil this 
residue for fifteen minutes in oOc. c. of strong solution of sodic 
carboiuite. add 100 e.c. of boiling water, filter while still hot. aiul 
wash the filtei' and contents with boiling water till the sodic salfee 
are washed away. Dry the i-esidue. l)urn the filter aiid add its 
ash to the insoluble residue, heat this to redness, cool and weigh. 
Deduct the ash of filter and enter the balance as sand or insol- 
UHLE siiJ<'\TKS. The ditt'erence in weight between sand, and 
sand and silica, enter as simca. This sand and silica will res|)ect- 
ively represent the amount of these materials in five grams of air- 
dry soil, and these weights multiplied by twenty will give the ])er 
cent respectively of sand and silica in such soil. 

14. Ferric oxide iiad alumina. — To 200 c. c. of Solution A (in 
an Erlenmeyer flask) add NILHO to alkaline reaction (avoiding 
excess), to precipitate ferric and aluminic oxides and phosphates. 
Expel excess of ammonia l)y boiling, let it settle, decant the clear 
solution through a filter ; add to the fiask 50 c. c. of hot distilleil 
water, boil, settle and decant as before. After pouring off all the 
clear solution possible, dissolve the residue with a few drops of 
IICl. with heat, add just enough N^H4lI0 to })recipitate the 
oxides. Wash by decantation with 50 c. c. of distilled water, and 
then transfer all the precipitate to the filter, and -wash witli hot 
distilled water till the filtrate becomes free from chlorides. (Savi' 
the filtrate and washings. Solution 15.) Dry tlu^ Hltei' and pre- 
cipitate in the air-bath at llO*^. transfer the pivcipitate to a tared 
platinum crucible, l)urn the filter and add the ash to the precip- 
itate, heat the whole red-hot, cool in desiccator and weigh. The 
increase of weight — minus the ash of lilter ami the phosphoric 
acid (found in a separate pi-ocess) — represents the weight of the 
ferri(! and aluminic oxides. 

15. /•/■/■/•/'■ i>xiilf. — IMai'c the whole of the i<niited oxides in an 



Erlenmeyer flask (200 c. c. capacity), add 10 c. c. of coiic. Hz SO4 
aud digest on steam bath till complete solution is effected ; cool and 
add 100 c. c. of distilled water, a piece of amalgamated zinc and a 
slip of platinum foil, cover with a watch glass and allow to stand 
for twenty- four hours to reduce ferric to ferrous salt. When the 
reduction is complete, as tested by transferring on a glass rod a 
drop of the solution to a drop of ammonic-sulphocyanido on a 
white porcelain surface, pour the solution at once into a beaker, 
wash out the flask and transfer the washings to the beaker, taking 
special pains to exclude any zinc, mercury or other reducing 
agents, add 2 c. c. of Hs SO*, make up the solution to 250 c. c. with 
pure recently-boiled water aud titrate with standard solution of 
permanganate for the ferric oxide pj'esent in two grams of uir-dry 
soil. 

Pre2)arafiou of standard penmmganatc solution. — Dissolve 
3.15G grams of pure crystallized permanganate of potassium in 
1,000 c.c. of distilled water at 16°, and preserve this in ground-glass 
stoppered bottle, shielded from the light. Standardize this solu- 
tion with pure ferrous sulphate or ammonic-ferrous sulphate, or 
oxalic acid, according to directions in Johnson's Fresenius, § 113, 
or Sutton's Volumetric Analysis, § 30, and determine the equiva- 
lent weight of FeaOs for each c. c. of the permanganate solution. 

The weight of ferric oxide deducted from ferric oxide and 
alumina (14), with corrections for filter ash and phosphoric acid, 
will give the weight of alumina in two grams of air-dry soil. 

10. Manganese. — Concentrate the filtrate and washings from 
B to 200 c. c. If a qualitative test of the soil shows the presence 
of manganese, add a few drops of bromine to the solution till the 
color becomes orange, and keep the solution at the temperature of 
60"^ for twenty-four hours. The manganese will separate as a 
brownish hydrate, Mna O2 (OH) 2. Filter, wash the precipitate, 
dry, and heat to redness, weigh and estimate as Mn., O4. 

17. Lime. — If no manganese is preci^jitated, add to solution B, 
or the filtrate and washings (from 16), 20 c. c. of a strong solution of 
NH4 CI and 4:0c. c. of saturated solution of (NH^)! (Ja O4 to com- 
pletely precipitate all the lime as oxalate and convert the mag- 
nesia into soluble magnesic oxalate. Heat to boiling and let 
stand for six hours till the calcic oxalate settles clear, decant the 
clear solution onto a filter, pour 50 c. c. of hot distilled water on the 
precipitate and again decant the clear solution on the filter, trans- 
2 



/ 
10 

fer the precipitate to tlie Hlter and wash it free from all traces of 
oxalates and chlorides. Place the funnel over the mouth of a 
500 c. c. Erleumeyer flask, puncture the apex of the filter with a 
glass rod, wash the oxalate into the flask with a jet of watei', dis- 
solve any adhering oxalate from the filter by dilute H, SO, (ten 
per cent solution), wash the filter with a stream of distilled 
water, add to the flask 20 c. c. of II 4 SO4, make the volume up to 
300 c. c, heat to 70° and titrate with a standard solution of per- 
manganate of such strength that one cubic centimeter will be 
decolorized by .0063 grams of crystallized oxalic acid. Each 
c. c. of permanganate solution will represent .0028 grams of 
CaO. 

18. Alternate method. — Transfer the washed and dried oxalate 
to a tared platinum crucible, burn the filter on the crucible 
cover, add the ash to the precipitate, cover this with cone. 
H2 SO*, heat gently to dryness, and then intensely to expel excess 
of H2 80-1, cool in desiccator, and weigh. Estimate the increase 
of weight, minus filter ash, as calcium sulfate. Ca SO4 X .-11158 
= CaO. 

19. Second alternate niefliod. — Transfer the precipitate to a 
tared platinum crucible, l)urn the filter and add this to the pre- 
cipitate, heat the crucible and contents to low red heat to burn 
the oxalate. Moisten the cooled mass with a saturated solution 
of ammouic carbonate, dry and heat cautiously to low red heat, 
cool and weigh. The increase of weight (minus filter ash) rep- 
resents calcic carbonate, Ca CO3 X -oO = Ca O. 

20. Mayneaia. — Concentrate the filtrate and washings (from 
17) to 200 c. c, place in half liter Erleumeyer flask, add 30 c. c. of a 
saturated solution of Na^llPO*, and 20 c. c. of cone. NIUIO, cork 
the flask and shake violently at intervals of a few minutes till 
crystals form, then set the flask in a cool place for twelve hours. 
Filter oft" the clear liquid through a tared Gooch filter, transfer 
the precipitate to the filter and wash with dilute ammouic hydrate 
(1: 3) till the filtrate is free from phosphates; dry and ignite 
the crucible, at first gently and then intensely, to form mag- 
nesium pyrophosphate. The increase of weight X .36021 = MgO. 
By using an Erleumeyer flask free from scratches and marks, 
and shaking violently instead of stirring with a glass rod, the 
danger is almost entirely avoided of crystals adhering to the sides 
of the vessel. But if crystals do adhere they are Jis readily removed 



11 

by a rubber tipped glass rod from an Erlenmeyer flask as from a 
beaker. 

21. Sidfuric add. — Evaporate 200 c. c. of Solution A (12) 
nearly to dryness on a water batli to expel excess of acid, then add 
100 c. c. of distilled water; heat to boiling and add 10 c. c. of solu- 
tion of BaCla, and continue the boiling for five minutes. When 
the precipitate has settled, pour the clear liquid on a tared Gooch 
filter, heat the precipitate with 50 c. c. of boiling water, and trans- 
fer the precipitate to the filter and wash with boiling water till the 
filtrate is free from chlorides. Dry the filter and ignite strongly. 
The increase in weight is barium sulfate, which X .34331 = 
SOs in two grams of air-dry soil. 

22. Phosphoric arid. — To the filtrate and washings from 21 
add NIKHO to alkaline reaction, then (NH4)2C03 and a few 
drops of (NHi)2 C2 04 to complete precipitation ; boil, settle and 
decant the clear solution on a filter, add boiling water to the pre- 
cipitate and again decant ; finally bring the precipitate on the 
filter and wash thoroughly. Dissolve the precipitate in HNOs, 
and add molybdate of ammonium in excess to the solution. Keep 
at temperature of 70° for six hours, and from the phospho- 
molybdate of ammonium, estimate the phosphoric acid in the 
usual way. 

The material used in estimation of ferric oxide and alumina 
(14) may also serve for a separate estimation of P2 Oo. After 
titration with pennanganate, heat the solution to boiling and pre- 
cipitate with NlhllO. Wash the precipitate by decantation, 
dissolve in bot IINO3 and precipitate by ammonic molybdate as 
before, and estimate as pyrophosjjhate of magnesia. The pyro- 
phosphate X •ti39G ^ P2 Og, In estimating the alumina in the 
mixed precipitate of ferric and aluminic oxides and phosphates, 
the P2 O5 must be subtracted to obtain the final weight of alu- 
mina. Thus, from the final weight of the precipitate, by 
NH4H() (14) subtract the filter ash, the ferric oxide as determined 
by titration, theii the P-/)b, and the remainder will be AU Oa. 

The solubility of the phosphates in the soil is intimately related 
to their availability for growing crops. It has been assumed that 
phosphates solitble in acetic acid are active and immediately 
available for crops, and that soils containing acetic-soluble phos- 
phates will not be benefited by the use of super-phosphates. To 
determine the solubility of soil phosphates, boil ten grams of soil 



12 

in oUc. c. of strong iicotic acid for tifteen minutes, filter, evaporate 
the filtrate to dryness, ignite, dissolve the residue in 1I]S'0> with 
heat, and test the solution with excess of molybdate of aninioniuni 
at 70°. 

23. Fofash and soda. — Evaporate the filtrate and washings 
(from H'l) to dryness, heat to low red heat to decompose oxalates 
and expel ammonia salts, dissolve in 25 c. c. of distilled water, filter 
and wash the precipitate, add to the filtrate and washings 10 c. c. 
of baryta water, and digest for an hour. Filter and wash precip- 
itate, add amnionic carbonate to the filtrate to complete precipi- 
tation of baryta, filter and wash this precipitate. Evaporate the 
filtrate and washings in a tared platinum dish, gently ignite the 
residue to expel ammonic salts, cool and weigh. The increase of 
weight represents the chlorides of potassium and sodium in two 
grams of air-dry soil. 

Separate and estimate the potassium chloride by platinic chlor- 
ide according to the official method of the Association of Agri- 
cultural Chemists. 

Subtract the weight of potassium chloride as thus found from 
the weight of potassium chloride and sodium chloride. The differ- 
ence represents sodium chloride. 

Alternate method. — For alternate method for alkalies, use J. 
Lawrence Smith's method as given in (Jrook's Select Methods, 
second edition, pp. 28 to 40. 

24. Other alkali tnetah. — The salts of lithium, caesium aiul 
rubidium are occasionally found in very small amounts in soils. 
The agricultural uses of these salts are still in question, and their 
amount is too small to admit of quantitative estimation. A quali- 
tative examination may be made by the spectroscope with tlu' 
water-soluble materials (8) evaporated to dryness and dissolved 
with two or three drops of IICl. Test by spectroscope with plat- 
inum wire in Bunsen flame. 

25. Xih'oi/t'N of the soil. — The com])iiic(l nitrogen in the soil 
and the state of combination in whic^h it is held are subjects of 
great importance to the agricultural chemist. The niti-ogen com- 
l)ounds in tlu! soil are usually placed in three classes: 

1. The nitrogen combined with oxygen as nitrates oi' nitrites, 
existing as soluble salts in the soil. 

2. The nitrogen combined with hydrogen as aimnoiiia. or 
organic nitrogen easily (jonA'ertible into ammonia. The annnoiiia 



13 

may exist as suits or be occluded by liydnited ferric or aluminic 
oxides and organic matter in the soil. 

3. The inert nitrogen of the soil or the humose nitrogen. 

The nitrogen in the first and second classes is considered the 
active nitrogen of the soil so far as plant food is concerned, while 
the inert nitrogen is, for the time being, incapable of aifording 
sustenance to agricultural plants, and hence is properly jjlaced in 
a class by itself. But the exchanges between the first and second 
classes are well known to chemists ; the reduction of nitrates to 
ammonia, and the oxidation of ammonia to nitrates are familiar 
to agricultural chemists. It has also been a matter of discussion 
which of these forms is best fitted to nourish plant life. They 
seem to have equal agricultural activity, and their exchanges arc 
matters of almost daily occurrence. Why should they be separ- 
ately estimated in an agricultural chemical analysis? Why not 
class them together as active soil nitrogen and estimate their 
amount in one operation ? 

26. Active soil nitrogen. — The material proposed for reducing 
the nitrates to ammonia, and at the same time to bring ammonia 
salts and organic nitrogen into condition for separation by distil- 
lation, is sodium amalgam. Liquid sodium amalgam may be 
readily prepared by placing 100 c. c. of mercury in a flask of 
half liter capacity, covering the warmed mercury with melted 
paraffine and dropping into the flask at short intervals metallic 
sodium the size of a large pea (taking care that the violence of the 
reaction does not^ project the contents from the flask), till 6.75 
grams of sodium have combined with the mercury. This amal- 
gam contains one-half of one per cent of sodium, and may be 
preserved indefinitely under the covering of paraffine. The mer- 
cury is easily recovered at the close of the operation, and nothing 
of value is wasted except the sodium. 

To estimate the active soil nitrogeii, weigh fifty grams of air- 
dry soil and place it in a clean mortar. Take 200 c. c. of ammonia- 
free distilled water, rub up the soil with a part of the water to a 
smooth paste," transfer this to a flask of one liter capacity, wash- 
ing the last traces of the soil into the flask with the rest of the 
water. Add 25 c. c. of the liquid sodium amalgam, and shake the 
flask so as to break the sodium amalgam into small globules dis- 
tributed through the soil. Insert a stopper with a Kroonig valve 
and set aside in a cool place for twenty-four hours. Pour into 
the flask 50 c. c. of milk of litne aiul distil on a sand bath 100 c. c. 



14 

into a flask containing 20 c. c. of decinormal sulfnric acid, and 
titrate with decinormal soda solntion, nsing dimethyl orange as 
indicator. Estimate the nitrogen of tlie ammonia found as 
art ire soil nitrofjoi. 

If the ammonia produced is too small in amoujit to be readily 
estimated volumetrically, determine the ammonia by Nessleriz- 
ing the distillate. , 

27. Estiination of nitrates in the soil. — When it is desired to 
estimate separately the nitrates in the soil the following modifica- 
tion of 20 nuiy be used : Evaporate 100 c. c. of the soil extract (8) 
to dryness on the water bath ; dissolve the soluble portion of the 
residue in lOOc. c. of amnionia-frce distilled water, filtering out any 
insoluble residue, place the solution in a llask ami add 10 c. c. of 
liquid sodium amalgam, insert stopper with Kroonig valve, set it 
aside to digest in a cool place for twenty-four hours, add 50 c. c. of 
milk of lime, distil and titrate as in 20, ami estimate the nitrogen 
as Ns 0.. 

Nesslerizing may be substituted for titration when the amount 
of nitrates is small. 

An approximate estimation of the amount of nitrates will be 
of value in determining which method of estimation to use. 
This may be done by evaporating a measured quantity of the soil 
extract (8) say See, more or less, on a porcelain cover on a steam 
bath or radiator, having first dissolved a minute fragment of pure 
sulfate of brucia in the soil extract. Wlien dry, pour over the 
residue concentrated sulfuric acid free from nitTates, and observe 
the color reactions j) rod need. 

If the nitrate (reckoned as KNOs) left upon evaporating the 
quantity of water taken cloes not exceed the two thousandths part 
of a milligram, only a pink color will be developed by adding the 
sulfuric acid; with the three thousandths part of a milligram, a 
pink with faint reddish lines; with the four thousandths part, a 
reddish (tolor; with the five thousandths part, a red color. 

By increasing or diminishing the amount of soil^extract evap- 
orated to setuire a color reaction of a certain intensity, an approx- 
imate estimate may l)e made of the amount of nitrates present. 

Blank experiments to test the acid, and the brucine will be 
required Ijcfore confidence can be placed in such estimation. 

28. Total niirofjen of soils. — The total nitrogen of soils may be 
determined l)y the usual combustion with soda-h'mo, but this 



15 

process is often uusatisftictory, because of tlie large amount of 
material required when the organic matter or humus is in 
small amount. 

A modification of the KJeldahl method is more easy to carry 
out, and gives results equally satisfactory. Weigh out twenty 
grams of air-dry soil, place this in a Kjeldahl flask and pour in 
20 c. c. of sulfuric acid (free from ammonia) holding in solution one 
gram of salicylic acid. (If the soil contains much lime or mag- 
nesia in the form of carbonate, enough more sulfuric acid must 
be added to secure a strongly acid condition of the contents of 
the flask.) Add gradually two grams of zinc dust, shaking the 
contents of the flask to secure intimate mixture. Place the flask 
in a sand bath and heat till the acid boils, and maintain the boil- 
ing for ten minutes. Add one gram of mercury and continue 
the boiling for one hour, adding 10 c. c. of sulfuric acid if the con- 
tents of the flask are likely to become solid. Cool the flask and 
wash out the sohible materials in the flask with 200 c. c. of pure 
water, leaving the heavy earthy materials in the Kjeldahl flask. 
Kinse the residue with 100 c. c. of water and add this to the first 
washings. Place this soluble acid extract in a liter digestion 
flask, add 35 c. c. of solution of potassium sulphide and shake the 
flask to secure intimate mixture of the contents. IntToduce a 
few fragments of granulated zinc, pour in 75 c. c. of saturated solu- 
tion of caustic soda, connect the flask with a condenser and dis- 
til 150 c. c. into a fl>isk containing 20 c. c. of decinormal sulfuric 
acid, and titrate with decinormal soda solution, using cochineal or 
dimethyl orange as indicator. 

Enter the nitrogen found in this operation as total soil nitroffcn. 

The difference between the total soil nitrogen and the active 
soil nitrogen will express the inert nitrogen of the soil. 

2U. Acid soils. — Soils of good agricultural quality are usually 
neutral or slightly alkaline, but soils are found Avhicli give a deci- 
dedly acid reaction when blue litmus paper is pressed upon the 
moist surface. Swamp muck is often acid from the presence of 
humic acid. Drying the muck removes the acid quality by 
rendering the muck insoluble in water. If an acid soil becomes 
neutral by drying, and the water filtered through the dried soil is 
free from acidity, it is probable that the acid condition was caused 
by an organic acid of the humus class. But if the acid condition 
persists after drying tlie soil, the cause is to be sought in sulfates 
of some heavy metal, e. g., iron or copper, whose sulfates have 
an acid reaction. 



Ml^yniOl) 1011 ANALYSIS OF ASHES. 



PUEI'A RATIO X OF Asil. 

The material before combustion must be thoroughly cleaned 
from all foreign matters, especially from adhering soil: woods, 
barks, roots, etc., by brushing and dusting, wiping with a moist 
s[)onge, and linally by rublnng gently with a soft cotton cloth; 
seeds by placing on a line sieve and drenching them with distilled 
water with constant shaking till the water runs ofp clear, and 
linally rubbing the seeds between a soft cotton cloth. The ma- 
terial should then be dried to constant weight at the temperature 
of bailing water. 

Combustion of Organic Substances. 

The combustion should be carried on at a comparatively low 
temperature, never reaching a full red heat, because of danger of 
volatilizing alkaline chlorides, etc., nor in a strong draught of air 
lest the lighter parts of the ash, e. g. , silica, be carried away. 

C'ombustion is best carried on in a Hat platinum dish in a cast- 
iron muffle, eighteen inches long, three and a half inches high, 
and five inches wide at the bottom, the muffle resting on a fire- 
])rick inside the furnace to moderate the bottom heat, and the 
fuel piled upon the top and sides of the muffle to burn the ma- 
terial by surface heat. 

When this " Lawes & Gilbert muffle" is not at command the 
ordinary assay furnace may be used by placing a fire-brick under 
the muffle, placing the platinum dish and material for combus- 
tion near the middle of the muffle, feeding the furnace with fuel 
on the top and sides of the muffle so- as to maintain it at a low 
red heat, and leaving the plug of the muffle so as to allow a very 
slow draught of air. 

When no muffle of any kind is available the substance may be 
burned to ash in a platinum dish properly guarded. In place of 
■ a muffle use the sheet-iron dish commonly employed for a four- 
inch sand-bath. Place the empty sheet-iron dish on an iron 
tripod or other support, so that the gas flame from a Buusen 



1? 

burner may cover the whole bottom of the dish. On this dish 
place a sheet-iron cone (of Kussia iron), six inches high, three 
and a half inches in diameter at the bottom, and one inch at the 
top. 8uch dish-and-eone-cover approximates the condition of a 
muffle for materials ])laced inside the cone. 

For the incineration use a tiat-bottomed platinum dish, three 
inches in diameter and one inch deep. Place the material for 
combustion in the platinum dish, jnit this in the empt}- sheet- 
ii'on dish, place over the platinum dish and inside the sheet-Iron 
dish the sheet-iron cone, and heat the sheet-iron dish to low red 
heat by gas flame. The cone should be made of Russia sheet- 
iron to avoid the danger of scales of iron rust falling into the 
ash during combustion. 

The cost of such combustion a^jparatus is snuill and the mani})- 
ulation simple, the platinum dish and contents will not be 
heated to volatilizing alkaline chlorides, there Avill not be sufficient 
draught of air to carry away any ash, yet the heat within the cone 
will slowly and securely incinerate the contents of the dish. 

With substances rich in silica and alkalies it is better to lirst 
char the substance. \\'ash with distilled water to remove soluble 
salts, then dry and incinerate the residue. Evaporate the watery 
extract and add this to the rest of the ash. 

With substances rich in phosphates, e. g., seeds and animal 
substances, char the material and remove salts by acetic acid, 
decant the acetic solution, wash with distilled Avater, and then 
complete the combustion. Add the acetic solution and washings 
to the final ash, evaporate to dryness, and gently ignite the whole 
to decompose the acetates. By this method seeds, etc., may be 
incinerated in eight to ten hours. 

In whatever way obtained the whole of the ash should be pn]- 

verized and intimately mixed before analysis: %* ^ 

A, ' '^ 

AxAiAsis OF Wood Ashes. 

Weigh out one hundred grams of air-dry ashes, and pass them 
through a smm- sieyey(1a v.eni^i r it^>Lub Lu Lliu in^jfe -)- to separate 
materials manifestlv/foreign, e. g., nails, broken glass and pot- 
tery, pebbles, ep»f\iind estimate the per cent of such accidental 
material&--''lnilverize any charcoal and semi-fused portions of 

rTremaining on the sieve, sift them and mix intimately with 
the sifted ashes, and preserve in stoppered bottles for analysis. 

y-^ Moisture. — ^^'eigh out five grams of these ashes in a tared 



platinum dish and lieat to llO*^ C, in air bath to constant weight. 
Cool in desiccator, and weigh. The loss of weight X ^0 = per 
cent of moisture in the ash. 

2^ Carbon. — Heat this dried ash in platinum dish in the sheet- 
iron ani cone apparatus described for incinerating organic sub- 
stances till the ash is uniformly grayish-white and there is no 
further loss of weight; weigh and determine this loss of weight, 
which X 2*^ =^ P'^"" ^^^^ of charcoal in original ash. 

3^ Sand and .silica. — Pla^e this ignited ash in a four-ounce glass- 
stoppered vial; measure out 50c. c. of HCl (sp. gr. 1.115) and pour 
on the ash cautiously to prevent loss of ash by spurting, and 
when all etfervescence has ceased, add the balance of the acid, 
insert glass stopper, wire it securely, and place in steam bath 
(described under soil analysis) for two hours; empty the vial into 
a })latiuum dish, wash the vial with distilled water, adding the 
washings to the ash solution, and evaporate the whole to dryness 
on water bath. A'dd 10 c. c, dilute HCl and 50 c. c. of distilled 
water to the contents of the platinum dish, transfer the contents 
to a Schleicher & Schuell filter, wash with distilled water till the 
last drops of filtrate are free from chlorides (when tested by solu- 
tion of Ag NOs), dry and ignite the precipitate and filter. If 
there are no grains of sand (revealed by grittiness when stirred 
with a gla?s rod), subtract the ash of the filter from the weight 
of tliis residue und estimate the balance as silica. If sand is 
present, boil the ignited and weighed residue in strong solution 
of Nas COs to dissolve silica, wash by decantation to remove all 
soda salts, dry and weigh the sand, the ditference between tlie 
weight of sand and silica + sand, will give the weight of silica, 
and this X ^^ ^ P^r cent of silica in the ash. 
/^# r '^° ^^'^•V^^'''^''i(' n<^id. — Evaporate the acid, filtrate and washings 
4^^ A^fronTsTlicato 100c. cTTpTac^his in an Erlenmeyer flask of 250c. c. 
capacity, add NH4 HO till nearly neutralized, then add 30 c. c. of 
citro-magnesic* mixture, then 30 c. c. of cone. Nir4ll(), cork 

* The citro-iHagaesic mixture is prepared by*"dissolvuig-two liuudred 
and seventy grams of citric acid in 350 c. c. of warm water and adding, 
by degrees, twenty -seven grams of IMg COs. When effervescence ceases 
and the Hquid is cool add 400 c. c. of dilute (I to 10) ammonic hydrate, 
and dilute the whole to a liter. Preserve in a well-stopi)ered bottle. In 
the presence of a large excess, of NH3, 30 c. c. of this mixture will insure 
the ])re(ipitatiou of a decigram of P.j Ob even in the presence of ferric 
and ahuninic salts, unless tlieir <[uantity is excessive. 

See Suttcm's Volumetric Analysis, 5th edition, page 239. 



19 

the flask and sliake the flask and contents violently at inter- 
vals of a few minutes till crystallization is well established. 
Set the flask in a cool place for four hours, then filter out 
MgNH4P04 on a tared Gooch filter, wash the precipitate 
with dilute ammonia (1 to 3), dry the Gooch filter, ignite, 
at first gently and then intensely, to form pyrophosphate of 
magnesia. The increase of weight of the Gooch filter equals the 
pyrophosphate of magnesia from five grams of ash. This multi- 
plied by *7j7^^e|;X.6396 X ^== l^rff^, will give the percentage 
of Pz Oa^M ashes. '^y/^t 

In this method it is important to remove all the silica before 
precipitating the phosphoric acid. It is also essential to use so 
much of the citro-magnesic mixture as to prevent the precipita- 
tion of jDhosphate of iron or alumina. If the addition of the 
citro-magnesic mixture causes an immediate precipitation, the 
jsrecipitate is ferric or aluminic phosphate, and not enough of the 
citro-magnesic mixture was used. In this case the process must 
be renewed from the separation of silica, and the amount of 
citro-magnesic mixture increased till no precipitate forms im- 
mediately after its addition. In this case the addition of NH4HO 
in excess will cause the complete precipitation of phosphate of 
magnesia and ammonia after a time, while ferric and aluminic 
salts will be held in solution. 

Alternate metliod. — Molybdate of ammonia. The official method 
for analysis of insoluble phosphates as prescribed for determina- 
tion of total phosphoric acid is recommended as the alternate 
method. 

5° Carhonic acid. — Heat four or five grams of ash in the sheet- 
iron and cone muffle till all charcoal is consumed; cool in a des- 
iccator, weigh out two grams of ash and transfer to a Schroetter 
alkalimeter. Fill one. chamber of the alkalimeter with HNOs 
(sp. gr. 1.2) and the other with cone. H2SO4 to dry the escap- 
ing CO2. Wipe the outside of the alkalimeter from every trace 
of dust and moisture, and weigh the apparatus. Open the stop- 
cock of the HN()3 chamber and permit the acid to flow so as to 
decompose the ash slowly, the COs bubbling up, a bubble at a 
time, through the H2SO4. AVhen effervescence ceases let the 
whole of HNOa flow into the reservoir below, attach a CaGla tube 
to the top of HN()3 chamber, heat the alkalimeter on sand bath 
to gentle ebullition and suck dry air through the apparatus till 



(lOi is removed. Set aside the alkaliiiieter till it becomes cold, 
and then weigh the apparatus. The loss of weight will rc^pre- 
sent the weight of C'Oi in two grams of ash. 

AUcrnalr iiii-fhniL — By Liebig's potash bulbs. The usual 
process of absorption by solution of KIIO, weighing, etc. 

6'° C/tloriiic. — Pour out the nitric solution from the alkali- 
meter upon a filter, wash out the last traces of the solution,, pass 
the soluble matters through the filter and wash tlie insoluble res- 
idue with the water acidulktetl.witli IINOa. To mis filtrate add 
solution of AgXOs to complete precipitation of the chlorides, 
boil and stir with a glass rod till the silver chloride separates in 
rtocks, let it settle, decant the clear li(|uid upon a filter, add 
100 c. c. of water acidulated with IIXOs and heat to boiling, again 
decant the clear liquid upon the filter and wash the precipitate 
with boiling distilled water; finally bring the precipitate upon 
the filter and wash with distilled water till the filtrate gives no 
reaction with dilute HCl. Dry the precipitate thoroughly and 
transfer to a tared porcelain crucible with cover, ignite the filter 
on the crucible cover, moisten the ash with a drop of HCl, evap- 
orate the excess of acid, place the lid on the crucible and heat 
the crucible till the silver chloride begins to melt around the 
edges. Cool the crucible and weigh. The increase of weight 
(minus the filter ash) multiplied by .1236 (i. e. ^^ X 50) will give 
the per cent of chlorine in the ash. 

This process should be carried on in the absence of direct sun- 
light. 

Alt I', mat)' inrlliiKl. — Boil ten grams of ash in 4()() c. c. of pure 
water for half an hour; transfer all to a measuring flask of 500 c. c. 
capacity, wash the beaker and add the washings to the flask, 
cool, make up the volume to 500 c. c. and mix intimately. Filter 
off through a dry filter 100 c. c, add a drop of solution of plienol- 
phthalein, and neutralize with dilute HXOs till only a faint pink 
color renuuns, add two drops of strong solution of Ka Cr ()« and 
titrate with standard decinormaj solution of Ag XOs (10.95G grams 
AgNOs @ 1000 c. c). Every c. c. of the standard silver solution 
equals .003540 grams of chlorine in two grams of ash, or c. c. X 
.1773 = per cent of chlorine in ash. 

In [jcrt'onning this titration, watch the reacticm through a 
plate of amber colored glass of such tint as will neutralize the 



21 

color of potassic ehromate. The reaction to form silver cliro- 
mate then becomes sharply defined. 

The reliability of this method will depend upon the accuracy 
with which neutralization by nitric acid has been made. The 
least trace of free acid or alkaline carbonate will vitiate the results. 

Second alternate metliod. — To 100 c. c. of the solution in the fore- 
going method add HNOa to strong acid reaction, then solution 
of AgNOs to complete precipitation, and then proceed as in the 
first method for estimating chlorine. 

These alternate methods are based on the assumption that 
boiling water will dissolve all the chlorides present in wood ashes. 

7° Sulfuric acid. — Place five grams of ash in a digestion vial.- 
Measure out 50 c. c. of HCl. (sp. gr. 1.115) and cautiously pour 
the acid on the ash till efEervescence ceases, then pour in the rest 
of the acid, place the glass stopper in place and wire it securely, 
and place the vial in the digestion steam bath for two hourr. 
Pour the contents of the vial into a 250 c. c. measuring flask, wash 
out the vial and add tlie washings to the flask, cool, make up to 
250 c. c. with distilled water and mix intimately. Filter through a 
dry filter 100 c. c. into a beaker, and evaporate on water bath till 
excess of acid is expelled; add 100 c. c. of distilled water, heat to 
boiling temperature and precipitate with BaCb in excess. Let it 
stand foi; twelve hours in a warm place, then decant the clear 
liquid through a filter, add 100 c. c. of boiling water to the precipi- 
tate, let it settle and then pour ofl: the clear liquid through the 
filter, repeating the process till the filtrate is free from chlorides; 
finally transfer the precipitate to the filter, wash this with dis- 
tilled water, dry the precipitate and transfer it to a tared cruci- 
ble, separating the precipitate from the filter as completely as 
possible, burn the filter separately, letting the ash fall into the 
crucible, heat this to low redness, cool and weigh. Subtract the 
filter ash from the increase in weight and multiply the remainder 
by .34335 for 8O3 in two grams of ash. (Preserve the filtrate 
and washings for 11°, Estimation of a/kalies-. ) 

8° Oxide of iron. — Filter 100 c. c. of the original acid solution 
(for 7°) through a dry filter, nearly neutralize with ammonia 
water, then add a gram of sodic acetate and acetic acid till the 
odor of acetic acid is preceptil)le, boil to precipitate ferric phos- 
phate, filter while hot and wash precipitate with boiling distilled 
water till the filtrate is free from chlorides. Dissolve the ferric 



22 

precipitate on the filter with dilute HaSO* iuto a small Erleii- 
meyer flask, wash the filtrate, dry and ignite the same and add 
the ashes to the acid solution in the flask, reduce the ferric to 
ferrous salt by amalgamated zinc or by a coil of magnesium wire, 
till a drop of the solution gives no color, with NH* CyS. Pour 
off the solution of ferrous salt into a beaker, rinse the flask and 
add the rinsings to the beaker, add freshly-boiled distilled water 
to make 200 c. c. of the solution, add 2 c. c. of sulfuric acid, heat to 
70'^, and titrate with standard solution of permanganate, and esti- 
mate the iron as ferric oxide. 

9^ Lime. — Evaporate the filtrate and washings from ferric 
phosphate (8°) to 100 c. c. To the hot solution add 20 c. c. of con- 
centrated solution of ammonie chloride, and 40 c. c. of saturated 
solution of ammonie oxalate; boil the whole for ten minutes, and 
then let it stand in a warm place for six hours; decant the clear 
liquid upon a filter, wash the precipitate twice by decantation, 
then bring the precipitate upon the filter and wash it free from 
chlorides and oxalates, testing the washings by argentic nitrate. 
Puncture the point of the filter with a glass rod, wash the calcic 
oxalate into a 500 c. c. flask by a stream by the wash bottle, dissolve 
any oxalate adhering to the filter by dilute H2SO4 (1:10), add 
20 c. c. of H2SO4 to the flask and make the volume to 300 c. c. 
with pure water, heat to 70° and titrate with standard solution of 
permanganate in which each cubic centimeter of permanganate is 
equivalent to .0063 grams of crystallized oxalic acid. Each cubic 
centimeter of the permanganate solution used will be equivalent 
to .0028 grams of ( 'a O. 

Alternate itHtlmd for linw. — Dry the washed precipitate of 
calcic oxalate; transfer the oxalate to a tared crucible, burn the 
filter on a platinitm wire, letting the ashes fall into the crucil)le, 
heat the crucible to low red heat, cool and moisten the contents 
witii a saturated solution of amnionic carbonate, dry and heat 
carefully to low red heat to expel amnionic salt, cool and weigh. 
Subtract the weight of filter ash, and estimate the increased 
weight as Ca C'Os. 

Second alternate method for lime. — Dry the washed preci]iitate 
(tf calcic oxalate, transfer to a tared platinum crucible, burn the 
filter and add the ash to the contents of the crucible. Overflow 
the calcic oxalate with cone. HaSO , heat gently to dryness, and 
then intensely to ex))el excess of lIaS04, cool in desiccator and 



23 

weigh. The increase of weight, minus filter ash, estimate as 
calcic sulfate, Ca SO4 X .41158 = Ca 0. 

10'^ Magnesia. — Evaporate the filtrate and washings from calcic 
oxalate to 200 c. c, pour into a clean and unscratched Erlenmeyer 
flask of 500 c. c. capacity, add 30 c. c. of strong solution of 
(]SrH4)2HP04 and 50 c. c. of cone, ammonia hydrate, cork the flask 
and shake violently at intervals of a few minutes till crystallization 
is established, and then set aside for twelve hours in a cold place. 
When precipitated in this way crystals will seldom adhere to the 
sides of the flask, yet more perfect crystallization than when stirred 
with a glass rod. If crystals should form on the sides of the flask 
they are as readily detached by a rubber-tipped rod as in a beaker. 
Filter through a tared Gooch filter, wash the precipitate with 
amnionic hydrate, diluted with distilled water (1 to 3), till 
filtrate is free from phosphates (acidify a few drops of filtrate with 
nitric acid and test with molybdate of ammonia). Dry the pre- 
cipitate, ignite, at first very gently and then intensely, with blast 
lamp, to convert 2 Mg NH4 PO4 into Mga P2 Ot. Cool in desic- 
cator and weigh. The increase of weight X -30024: == Mg 0, in 
two grams of air-dry soil. 

11° Estimation of alkalies. * — Concentrate the filtrate and wash- 
ings from (7°) to 100 c. c, add NH4 HO and (NH4)2C20* to com- 
plete precipitation of barium and calcium, filter, wash the pre- 
cipitate, evaporate the filtrate and washings to dryness in plat- 
inum dish and ignite gently. Add to the residue concentrated solu- 
tion of oxalate of ammonia, evaporate to dryness and ignite gently. 
Dissolve residue in distilled water, filter from insoluble Mg 0, acid- 
ify the filtrate with HCl, and evaporate to dryness in a tared plat- 
inum dish and ignite gently. The increase of weight represents 
the chlorides of potassium and sodium in two grams of ash. 
Separate and estimate potassium by PtCl4, in the usual way, 
and the sodium by difference. 

* Test the filtrate from (7°) for lithia by the spectroscope with a loop 
of platinum wire moistened with the iiltrate, held in a colorless Bunsen 
flame. The quantity of lithia is usually too small to be determined 
gravimetrically, but it may be estimated by diluting the solution with 
distilled water till the lithia line is on the point of disappearing- from the 
spectrum when a loop of clean platinum wire moistened with the solu- 
tion is placed in the Bunsen flame. The wire must be clean for each 
trial, and no concentration of the salt by repeatedly evaporating the 
solution on the loop of wire without cleaning it. One part of Li CI in 
450.000 parts of water will show the lithia line in the spectrum. 



LIBRARY OF CONGRESS 







002 781 560 

J-^-' MdiKjtiiii'si'. — Manganese is not a usual constituent of wood 
aslies. Test the asiies for manganese by heating on platinum 
foil over a colorless Hunsen flame half a gram of ashes with a 
gram of sodic carbonate and a few grains of nitrate of potash. 
The green manganate of soda in the fused portion as it cools 
will show the presence of manganese. 

To estimate manganese, dissolve two grams of ash in lU'l. 
Evaporate excess of acid over the water bath, pour the whole on 
a filter and wash with distilled water to make 100 c. c, nearly neu- 
tralize with sodic carbonate, and then add half a gram of sodic 
acetate and 20 c. c. of strong bromine water and set the flask aside 
in a warm place for twenty-four hours, or until the bromine has 
nearly disappeared. Filter out the manganese oxide, wash thor- 
oughlj', transfer to tared crucible, heat gently, and then 
intensely, and estimate the residue as ^[na ()4. Mns ()< x .03013 
= Mn 0. 

The manganese may be precipitated by passing a stream of 
chlorine through the solution till fully saturated, instead of using 
bromine water. 

The ashes of mineral coal contain only a small amount of alka- 
lies and phosphates, but a large amount of insoluble material, 
clay, etc. Their value depends mostly upon the sulfate of lime 
and phosphate pi'esent. They are often decomposed with diffi- 
culty. They should be ground to a fine powder, and five grams 
placed in the digestion vial, with 50 c. c. of IIC'l (specific gravity 
l.llo) and digested in the steam bath for six hours, and the sol- 
uble portion analyzed in the usual way. 

The aluminic material is in so large proportion that it is better 
to use the m<)lyl)dic method for estimating phosi)horic acid, after 
eliminating solul)le silica. 




LIBRARY OF CONGRESS 



DDD27aiSt.Dli 



